EFFECT OF RECOMBINANT APROTININ ON PLATELET ACTIVATION IN PATIENTS UNDERGOING OPEN-HEART-SURGERY

The hemostatic effect of recombinant (r)-aprotinin was studied in 41 p atients undergoing cardiopulmonary bypass surgery. mow cytometry was u sed to measure the expression of glycoprotein 1b (GP1b) and alpha-gran ule membrane protein 140 (GMP-140) on platelets. Additional parameters studied were beta-thromboglobulin (beta-TG), fibrinogen, fibrinopepti de A, plasminogen, platelet count, and the amount of postoperative che st tube drainage. Chest tube drainage was significantly less in the r- aprotinin-treated patients (p < 0.001). The percentage of platelets ex pressing GMP-140 increased to 9.7% in r-aprotinin patients and to 12.1 % in controls during the surgery. The difference between both groups w as not significant. Both values returned to baseline the next day. GP1 b expression decreased in both groups by 33-38% during the surgery and returned to baseline the next day. GP1b expression and the plasma con centrations of fibrinogen, fibrinopeptide A, beta-TG, and plasminogen were not different in r-aprotinin and control patients. We conclude th at r-aprotinin reduces blood loss during cardiopulmonary bypass surger y, but the primary mechanism is likely not through a protective effect on platelets.